When you are talking about a way in which two people or things are different, use the pattern a difference in something (not ‘difference of’ or ‘difference about’):
✗ There is a big difference of grammar between Japanese and English.
✓ There is a big difference in grammar between Japanese and English.
✗ There are major differences about language and customs in various areas in Korea.
✓ There are major differences in language and customs in various areas in Korea.
You can use difference of with a number or percentage, when you are talking about the amount by which two things are different:
He secured 50.7 per cent of the vote against 49.3 per cent (adifference of 227 votes).
Difference of is also used in the phrase difference of opinion which means ‘a disagreement’:
On this issue there is a major difference of opinion between the British government and most business leaders.
Don’t use the expression make a difference to mean ‘recognize that two things are different’. Use make/draw a distinction:
✗ Children cannot always make the difference between fiction and reality.
✓ Children cannot always make the distinction between fiction and reality.
The expression make a difference (to) means to have an effect on someone or something, often a positive effect:
Changes to the age of retirement make a difference to the amount of savings people need.